Photographic material for the production of photographic records with tone value correction



Apr1l21, 1964 E, HELLMIG ETAL v E 3,130,053

PHOTOGRAPHIC MATERIAL. FOR THE PRODUCTION OF PHOTOGRAPHIC RECORDS WITH TONE VALUE CORRECTION Filed June 18, 1957 FIG./

MASK/N6 LAYER OF LOW SPEED M CONTINUOUS TONE LAYER OF HIGH SPEED H SUPPORT ANTlHALAT/ON LAYER I 3 Q H as FOG LEVELL A5 log. J-T

FIG. 2

INVENTORSI EHRHARD HELLMIG HE INZ BERGER BY QMW -A A TTORNE Y5 United States Patent 3,130,053 FHDTOGRAPHIC MATERIAL FOR THE PRGDUC- TIDN 0F PHOTOGRAPHIC RECDRDS WITH TGNE VALUE CQRRECTION Ehrhard Hellmig and Heinz Berger, Leveri-zusen, Germany, assignors to Agia Airtiengesellschatt, Leverirusen, Germany, a corporation of Germany Filed June 18, 1957, Ser. No. 666,343 Claims priority, application Germany June 26, 1955 1 Claim. (Cl. 96-68) It is known that black-and-white or monochrome photographic records, especially in the reproduction art, have tone value defects which are shown in defective definition of the highlights and/ or shadows.

Processes are already known for obviating these defects.

The essence of such processes is that the photographic record which has a normal tone value and requires correction is combined with a separate black-and-white record or copy of the same original, which record only contains the corrective for a certain type of tone value or for several tone values simultaneously.

It has now been found that a photographic material which is better suited for the production of photographic records corrected for tone value is one in which two superimposed light-sensitive silver halide layers of different speeds are used for the production of a continuous-tone image and a mask, the lower layer (continuous-tone layer) having a gamma value of at least 0.5 and less than 2 and the upper layer serving for the production of the mask having a gamma value which is at least one and a half times that of the continuous-tone layer, and a speed which is within the range of about to preferably to of that of the continuous tone layer.

Gamma is the tangent of the angle between the straight line portion of the characteristic curve and the exposure axis.

Relative speed is the distance along the exposure axis of the characteristic curves between the points which result from projection of those points of the characteristic curves which lay 0.3 over the fog level.

The two layers may be sensitive substantially in the same regions of the spectrum, i.e., they may be sensitive to the blue, the blue and green, or to the blue, green and red regions of the spectrum. Such a material has the advantage that it can be exposed by light sources which spectrally are of very different composition, for example arc light, incandescent lamp light, xenon light or mixed light, for example from mercury vapour and incandescent lamps, without the sensitivity of the masking layer being changed relatively to that of the continuous-tone layer. In accordance with the same inventive idea, it is also possible for panchromatic films, such as are used for the production of colour separation records, to be produced with improved highlight reproduction.

However, it is also within the scope of the present invention to use layers which are sensitive to diiierent regions of the spectrum. For instance, the masking layer may be blue sensitive, and the continuous-tone layer blue and green sensitive, or the masking layer may be blue and green sensitive and the continuous-tone layer blue, green and red sensitive or vice versa.

Furthermore, it is advantageous that the mask, after "ice processing, for example after development and fixing, can be reduced, for instance by means of Farmers reducer without the continuous-tone image sufieriug, this being possible because the masking layer is arranged above the continuous-tone layer.

In the accompanying drawing FIG. 1 represents a crosssection through a material of the present invention in enlarged scale and FIG. 2 represents schematically the characteristic curves of the material of FIG. 1 after exposure with white light and development in the developer of Example 1, AE being the relative speed of the continuous-tone layer H and the masking layer M.

The material of the invention may be exposed and processed in the usual manner. It is especially suitable for the reproduction of originals of all types in the printing art. Due to the diiierent speeds and gradations of the two emulsion layers of the materials there are obtained characteristic curves which have a steeper gradation in the highlights than in the other parts, thereby effecting an outstanding correction of the tone-value in the highlights.

Example 1 A silver bromide emulsion, which is optically sensitized by 3,3',9-triethyl-5,5-diphenyl oxacarbocyanine iodide (25 mg. per litre of emulsion) to the green part of the spectrum is cast on a transparent layer support consisting of acetyl cellulose to give a layer of 0.012 mm. thickness. A second silver bromide emulsion layer which is not optically sensitized is cast above the first-mentioned layer, this second layer having a thickness of 0.008 mm. and having a speed which is lower by a factor of 20 than the first layer. After exposure with incandescent lamp light or are light and development in the developer referred to below, the first-mentioned layer should have a gamma value of 0.9, while the masking layer should have a gamma value of 2.8. As an emulsion for the lower layer there may be used the emulsion disclosed in Fiat Final Report, 943, page 47, and as an emulsion for the outer layer the emulsion disclosed in Fiat Final Report, 360, page 24. This material is used for the production of photographic records, via a reproduction camera, of a blackand-white continuous-tone original. If both layers are optically sensitized for the green and red part of the spectrum, the material serves for the production of color separation records by exposure through color separation filters, a multicolor non-transparent picture serving as original.

Developer: Water cc 1000 p-Methylaminophenol-sulfate g 7.5 Anhydrous sodium sulphite g 40.0 Hydroquinone g 3.5 Anhydrous sodium carbonate g 30.0 Potassium bromide g 3.0

Development time: 4 minutes with diluted developer (one part developer: two parts water).

The above material may also be used for the reproduction of a negative image of an original. In this case a correction of the tone value in the shadows of the original is achieved.

What we claim is:

A photographic material for the production of photographic records with tone value correction, which material consists essentially. ,of a support and two superimposed silver halide emulsion layers arranged on the same side of the support, the inner layer having a gamma of at least 0.5 and less than 2, the outer layer having a gamma which is at least one and a half times that of the inner layer, and a speed which is within the range of about $1 to V of that of the inner layer as measured by the points on the characteristics curves which are 0.3 above the fog level, the slower emulsion having said higher gamma in the high exposure intensity region where i the gamma of the faster emulsion drops off, both of said emulsion layers being sensitive to substantially the entire visible light spectrum so that the tone value correction is obtained anywhere in that region.

References Cited in the file of this patent UNITED STATES PATENTS 2,202,026 Renwick May 28, 1940 2,226,639 Schinzel Dec. 31, 1940 10 2,258,187 Mannes et a1. Oct. 7, 1941 

